A method for achieving the Raman signal excited by the longitudinal component of radially polarized light is proposed in this paper to solve the problem that ordinary polarized Raman signal cannot detect samples with vertical molecular orientation. In this method, the focused azimuthally polarized light and radially polarized light are used to excite the sample, and then the Raman signals generated by the two excitation lights are calculated to obtain the Raman signals excited by the pure longitudinal light field. We use Si(0 0 1) samples and Si(1 1 0) samples to verify the feasibility of this method. This work has certain significance for measuring longitudinally oriented molecules and longitudinal molecular vibration modes by Raman scattering.